Conventionally, as a control apparatus for an internal combustion engine, there has been known one disclosed in PTL 1. This engine is provided with a supercharging device, an EGR device, and a water-cooled intercooler as an intake air cooling device. In the engine, to enhance charging efficiency, a supercharging operation is performed by the supercharging device, and intake air increased in temperature by the supercharging operation is cooled by the intercooler. Further, an intercooler cooling circuit is connected to the intercooler. The intercooler cooling circuit is provided with an electric pump for circulating coolant through the circuit, and a flow passage of an engine cooling circuit is connected to the intercooler cooling circuit. The engine cooling circuit is provided with three electric valves, and is configured such that coolant having a relatively high temperature from the engine cooling circuit (hereinafter referred to as the “engine coolant”) is introduced into the intercooler cooling circuit or the introduction of the engine coolant is stopped, according to open/closed states of the electric valves.
In the control apparatus, EGR control for recirculating part of exhaust gases from an exhaust passage into an intake passage is performed via the EGR device. Further, during execution of the EGR control, to prevent condensed water from being generated when intake air passes through the intercooler, an outlet temperature of the intercooler is controlled by a control method shown in FIG. 2 of PTL 1. That is, when the outlet temperature of the intercooler is not higher than a dew-point temperature as a generation temperature of condensed water, the engine coolant is introduced into the intercooler cooling circuit, whereby the outlet temperature of the intercooler is controlled such that it is higher than the dew-point temperature. On the other hand, during stop of the EGR control, the outlet temperature of the intercooler is controlled to a temperature lower than during execution of the EGR control due to a decrease in the dew-point temperature (PTL 1 (Paragraph number [0097], FIG. 7)).
Further, as another control apparatus, there has been known one disclosed e.g. in PTL 2. This control apparatus is applied to an engine equipped with an engine cooling circuit and an intercooler cooling circuit having respective arrangements similar to those in PTL 1. During low-load operation of the engine, the engine cooling circuit and the intercooler cooling circuit are shut off from each other, and an electric pump is controlled such that a detected temperature of cooling liquid flowing into an intercooler (hereinafter referred to as the “IC inflow cooling liquid temperature”) becomes equal to a target temperature. The target temperature is set to such a value as will make it possible to suppress the temperature of intake air during acceleration to thereby obtain excellent acceleration performance. From the above, the conventional control apparatus disclosed in PTL 2 is configured such that excellent acceleration performance is obtained when the engine shifts from low-load operation to high-load operation.